199991808 has 320 divisors, whose sum is σ = 671742720. Its totient is φ = 58392576.

The previous prime is 199991761. The next prime is 199991833. The reversal of 199991808 is 808199991.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 5405166 + ... + 5405202.

It is an arithmetic number, because the mean of its divisors is an integer number (2099196).

Almost surely, 2^199991808 is an apocalyptic number.

199991808 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 199991808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (335871360).

199991808 is an abundant number, since it is smaller than the sum of its proper divisors (471750912).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

199991808 is a wasteful number, since it uses less digits than its factorization.

199991808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 104 (or 82 counting only the distinct ones).

The product of its (nonzero) digits is 419904, while the sum is 54.

The square root of 199991808 is about 14141.8459898275. The cubic root of 199991808 is about 584.7955630158.

The spelling of 199991808 in words is "one hundred ninety-nine million, nine hundred ninety-one thousand, eight hundred eight".